Dynamic Voip Codec Selection Based on Link Attributes at Call Setup

1. A method of voice codec selection for a voice-over-IP (VoIP) call, the method comprising: receiving into a proxy server a session initiation request transmitted via a first network link from a first VoIP device, wherein the initiation request seeks initiation of a VoIP call with a second VoIP device, and forwarding the session initiation request via a second network link from the proxy server to the second VoIP device; receiving into the proxy server via the second network link from the second VoIP device a response to the session initiation request, and forwarding the response from the proxy server via the first network link to the first VoIP device; the proxy server testing and thereby determining link quality of at least one of the first network link and the second network link; and the proxy server adding a specification of the proxy-determined link quality to at least one of the session initiation request being forwarded to the second VoIP device and the response being forwarded to the first VoIP device, to enable at least one of the first VoIP device and second VoIP device to tailor voice codec selection based on the specification of the proxy-determined link quality.

2. The method of claim 1 , wherein the session initiation request comprises a Session Initiation Protocol (SIP) INVITE request, wherein the proxy server testing and thereby determining link quality of at least one of the first network link and the second network link comprises the proxy server testing and thereby determining link quality of the second network link; and wherein the proxy server adding the specification of the proxy-determined link quality to at least one of the session initiation request being forwarded to the second VoIP device and the response being forwarded to the first VoIP device comprises the proxy server adding to the SIP INVITE being forwarded to the second VoIP device a specification of the proxy-determined link quality of the second network link, so that the second VoIP device receives the specification of the proxy-determined link quality of the second network link when the second VoIP device receives the SIP INVITE, and so that the second VoIP device can then use the received specification of the proxy-determined link quality of the second network link as a basis to select one or more voice codecs acceptable for the second VoIP device for the VoIP call.

3. The method of claim 1 , wherein the session initiation request comprises a Session Initiation Protocol (SIP) 200 OK message, wherein the proxy server testing and thereby determining link quality of at least one of the first network link and the second network link comprises the proxy server testing and thereby determining link quality of the first network link; and wherein the proxy server adding the specification of the proxy-determined link quality to at least one of the session initiation request being forwarded to the second VoIP device and the response being forwarded to the first VoIP device comprises the proxy server adding to the SIP 200 OK message being forwarded to the first VoIP device a specification of the proxy-determined link quality of the first network link, so that the first VoIP device receives the specification of the proxy-determined link quality of the first network link when the first VoIP device receives the SIP 200 OK message, and so that the first VoIP device can then use the received specification of the proxy-determined link quality of the first network link as a basis to select one or more voice codecs acceptable for the first VoIP device for the VoIP call.

4. A method of selecting a voice codec for use in a voice-over-IP (VoIP) call, the method comprising: receiving into a proxy server a session initiation request transmitted via a first network link from a first VoIP device, wherein the initiation request seeks initiation of a VoIP call with a second VoIP device, and conveying the initiation request via a second network link to the second VoIP device; at the proxy server, testing and thereby determining link quality of the first network link; and using the proxy-determined link quality of the first network link as a basis to select a voice codec for use by the first VoIP device and second VoIP device in the requested VoIP call, wherein using the proxy-determined link quality of the first network link as a basis to select the voice codec comprises: (i) the proxy server transmitting to the first VoIP device a specification of the proxy-determined link quality of the first network link, and (ii) the first VoIP device receiving the specification transmitted from the proxy server, and the first VoIP device selecting the voice codec based on the received proxy-determined link quality of the first network link.

5. A method of selecting a voice codec for use in a voice-over-IP (VoIP) call, the method comprising: receiving into a proxy server a session initiation request transmitted via a first network link from a first VoIP device, wherein the initiation request seeks initiation of a VoIP call with a second VoIP device, and conveying the initiation request via a second network link to the second VoIP device; at the proxy server, testing and thereby determining link quality of the first network link; and using the proxy-determined link quality of the first network link as a basis to select a voice codec for use by the first VoIP device and second VoIP device in the requested VoIP call, wherein using the proxy-determined link quality of the first network link as a basis to select the voice codec comprises: (i) the proxy server transmitting to the first VoIP device a specification of the proxy-determined link quality of the first network link, and (ii) the first VoIP device receiving the specification transmitted from the proxy server and selecting a set of possible voice codecs based on the proxy-determined link quality of the first network link, wherein the voice codec is then selected from the selected set of possible voice codecs.

6. The method of claim 4 , wherein testing and thereby determining the link quality of the first network link at the proxy server comprises pinging the first VoIP device a number of times to determine a statistical measure of the link quality of the first network link.

7. The method of claim 4 , wherein the link quality of the first network link comprises at least one quality metric selected from the group consisting of delay, jitter, and packet loss.

8. The method of claim 4 , further comprising: at the proxy server, testing and thereby determining link quality of the second network link; and using the proxy-determined link quality of the second network link as a further basis to select the voice codec for use by the first VoIP device and second VoIP device in the requested VoIP call.

9. The method of claim 8 , wherein the link quality of the first network link comprises at least one quality metric selected from the group consisting of delay, jitter, and packet loss, and wherein the link quality of the second network link comprises at one quality metric selected from the group consisting of delay, jitter, and packet loss.

10. The method of claim 5 , wherein testing and thereby determining the link quality of the first network link at the proxy server comprises pinging the first VoIP device a number of times to determine a statistical measure of the link quality of the first network link.

11. The method of claim 5 , wherein the link quality of the first network link comprises at least one quality metric selected from the group consisting of delay, jitter, and packet loss.

12. The method of claim 5 , further comprising: at the proxy server, testing and thereby determining link quality of the second network link; and using the proxy-determined link quality of the second network link as a further basis to select the voice codec for use by the first VoIP device and second VoIP device in the requested VoIP call.

13. The method of claim 12 , wherein the link quality of the first network link comprises at least one quality metric selected from the group consisting of delay, jitter, and packet loss, and wherein the link quality of the second network link comprises at one quality metric selected from the group consisting of delay, jitter, and packet loss.